"Right." William glanced up at the common room, thinking of the passage there that led directly (after a winding, twisting half-kilometre of darkness) to the corridor next to the library. The last time he'd seen it, that hallway had been full of blood-covered House-elves and a dead kneazle, but it was worth a shot. He'd send an owl to Spencer and then test his luck. "I'll head back to the library."
Via a few other places, possibly; as much as he didn't want to be out there, he wanted students to be out there alone even less. There would be less faculty members on the higher levels, and if he could find a way to clear that corridor, they could get other groups of students into the library and to safety. Temporarily, anyway. "If you need to reach me, you can send an owl there."